Improvement in cane-juice evaporators



4 Sheets-Sheef i.

H BESSEMER Evaporating Pan.

Patented Mar. 8, I853,

AM- PHDTO-LITHO.C0.N.Y. (OSEORNE'S PROCE$SJ 4 Sheets Sheet 4.

H. BESSEMER.

Evaporating Pan.

AM. PHOTO-LITHO.CO.N.Y. (OSBORNE'S PROCESS) of the vessel containing thefluid to be evapoj urious effect on saccharinefluids, andto remedyUrvirnn STATES PATENT @rrrca HENRY YBESSEMER, OF BAXTER HOUSE, COUNTY OFMlDDLEsEX, EXGLAND.

IMPROVEMEN'I' IN CANE-JUlCE EVAPORA TORS.

S ecification forming part of Letters Patent No. 9,607, dated Mari-h 9,1353.

To all whom 2'23 may concern.-

Be it known that I, HENRY BESSEMER, of Eaxter House, Old Saint PancrasRoad, in the county of Middlesex, England, have invented or discoveredcertain new and useful improvements or mechanism for evaporating andconcentrating saccharine fluids without boiling or bringing such fluidsin contact with pipes or surfaces heated by direct contact wit-h fire orsteam; and I do hereby declare that the same are fully described andrepresented in the following specification, reference being had to thedrawings accompanying and making part of the same.

With regard to my invention of a method or methods of evaporating andconcentrating saccharine fluids without boiling or bringing such fluidsin contact with pipes or surfaces heated by fire or steam, in order thatit may be fully understood, and in what respect the same differs fromother methods of evaporating saccharine fluids already known orpractised, I will first give a brief description of some of thesemethods, and then proceed to explain the manner in which I accomplishthis object.

The evaporation of the saccharine juice of the sugar-cane has for a longperiod of time been effected by applying fire to the bottom rated, andthis method is still extensively used in the British Colonies and manyother coun tries; but it has been found that saccharine solutions whenexposed to ahigh temperature soon acquire a dark color, part of thesugar being converted into glucose and rendered nncrystallizable, inwhich form it is more generally known as molasses. To lessen this evilvarious modifications of apparatus have from time to time been used inwhich heat is transmitted'to the saccharine 'fluids by steam circulatingin pipes which pass through and among the fluid, and thus impart theheat necessary to boil it, and throw off the aqueous portion in the formof steam, it further being found that boiling by steam also produces aninwhich numerous attempts have from time to been made. The apparatusinvented by Howard for this purpose, and well known under'the name ofthe vacuum-pan, is intended to lessen such injurious effects bycausingthe fluid to boil and throw off vapor in a close vessel or pan, in whicha partial vacuumn is maintained by a suitable condenser and airpumps,the boiling-point of such fluid being lower in a vacnunrchamber thanwhen under the influence of the atmosphere. The heat, however, requiredto produce ebullition in the vacuum-pan is transmitted thereto bysteam-pipes which pass in and among the fluid to be evaporated, thelower side of the pan being double or jacketed, for the purpose also ofcontaining steam.

Since the period of Howardsinvention other means have been devised andpatented for evaporating saccharine fluids in such manner that the bulkof the fluid should be maintained below the temperature at which suchfluids boil in the open air. To effect this object Mr. Gleland inventedan apparatus in which a convoluted worm or tube is mounted on ahorizontal axis extending across the evaporating pan or vessel in suchmanner that a portion thereof is immersed in the fluid to be evaporated,to assist which steam is made to pass through the convoluted tube, andas it revolves upon its axis a thin coating of the fluid is taken upupon it and exposed to the action of tthe surrounding atmosphere. Inorder to heat the fluid to be evaporated, the pan or vessel isconstructed with a chamber below it containing steam, which steam, bycontact with the bottom of the evaporatingpan, transmits heat to thefluid in which the revolving tube is partially immersed. After thepublication of this invention a patent was obtained in England by Mr.Augustus Gradesden, whose invention consists of a revolving cylinder ordrum composed of bars or tubes. This drum is mounted on an axis, whichextends across the pan and at such a height above it that the bars ofthe drum as it revolves may dip into the fluid to be evaporated, athincoating of which is taken up upon them and exposed to the atmosphere,whereby it becomes cooled and assists iii-lowering the temperature ofthe fluid in the pan. The pan or vessel is usually inclosed in afurnace, and fire is applied directly to the under side of it for thepurpose of heating the fluid therein. In like manner plain circulardisks or plates of metal have been mounted 011 an axis and made to dipinto the fluid to be evaporated, and take up upon their surfaces a thincoating of it, which is thus exposed to the cooling influence of theinder, the rivets being countersunk and the atmosphere, and at thesame'time assists evaporation.

On the 15th of April, 1851, a patent was ob tained for England by Mr.Herman Schroder, for improvements in manufacturingand refl 11- ingsugar, the invention consisting of a combination of steam-pipes withrevolving disks. Other plans have also been proposed in which air hasbeen forced below the surface of the -fluid and allowed to bubblethrough it, and thus keep down the mean temperature of the bulk of thefluid below the point at which the same would boil in the open air.

Before entering into the details of my apparatus for evaporatingsaccharine fluids, I wish it to be understood that I have discoveredthat in all cases, and in all forms of apparatus in which solutions ofsugar are brought in corn tact with metal tubes or surfaces heated bysteam, the heat thus transmitted produces an injurious effect in suchsaccharine matter, and also that to prevent such injurious effects ofheat it is not sufficient that the mean temperature of the fluid shouldbe kept below the boiling-point of such fluid in the open air byexposing it in thin films or coatings to the cooling action of theatmosphere, while at the same time other portions of the fluid are incontact with metal heated by fire or steam, whereby the low meantemperature of the saccharine fluid in the pan is the joint effect ofexposing such fluid to an injuriously-high temperature on one set ofsurfaces and to an unnecessary cool one on others, and is not the resultof the application of heating media at a low temperature, as in myinvention, which is hereinafter described. In all cases where I applyheat to the bulk of the saccharinefluid in the pan, I

prefer that the surfaces used to transmit such heat shall not exceed atemperature of 140 or 150 Fahrenheit, and so ebullition cannot takeplace at this low temperature. I force large quantities of heated air,also, at about 140 or 150 Fahrenheit, in contact with the fluid, whichhas the effect of keeping it at a uniform temperature and of absorbingthe aqueous portions of such fluid, which pass off, in combination withthe air, in an invisible vapor.

The apparatus for carrying into effect my invention is represented insheet D of the accompanying drawings, whereof Figure 1 is across-section of it taken on the line A B of Fig. 4. Fig. 2 is alongitudinal vertical section of it taken on the line C D of Fig. 1.Fig. 3 is an end elevation of it. Fig. 4. is a side elevation of it, andFigs. 5, 8, 9,, 10, and 11 details of the same.

a is a tank or vessel (constructed of plateiron or other suitablematerial) for the purpose of containing water,which is kept at anydesired temperature by the pipes I), which pass through it, and areheated by steam. The upper part of the tank has a close cover rivetedthereto, which is hollowed out so as to form the sugar-pan o, thecentral part of which is accurately curved,forming a segment ofacylplates put together with butt-points, so as to leave no projectionson the inside of the pan 0. At each end of the tank there are formedbearings d and (P, for the purpose of supporting a large tubular axle,c, which is closed at one end by a suitable cover, 0. This coveriselongated, and forms an axis, 0, on which that end of the tube issupported. The opposite end tof the tube 0 is 0pen,and rests on thebearing (1. The tubular axle c has a screw-thread on it, as shown atff,Fig. 5. This thread is to be about a quarter of an inch in depth, and ofsuch breadth as to fit a plate of sheet metal, which is to beinsertedtherein. The distance between the convolutions I prefer to be from halfan inch to one inch but it is by no means limited to these dimensions.

Fig. 11 represents a plate of metal, having a circular hole in itscenter of about half an inch less in diameter than the axle c. The plate9 has a slit out in it at g, and each edge of the metal next to thisslit is reduced to half its thickness, in order that a similar edge ofanother plate may be riveted thereto without in creasing the thicknessat that part. This joint is shown on a large scale at Fig. 10. Twoplates thus united are represented at Fig. 9, where 2 shows the rivetedjunction; or,instead of this mode of uniting the plates, the edges maybeplowed and tongued, as represented at 7L in Fig. 8. A number of circularplates thus prepared are -sprung sufficiently to cause their under edgesto be inserted in the spiral groove or thread of the axle e, 011 whichthey are fitted and riveted together, the plates as suming the formrepresented in Fig. 9. The above-described modes of joining the platestogether constitute no part of my invention. When as many plates arethus put on as will occupy the spiral groove from end to end, a largescrew will be formed by them, as repre sented by Figs. 2 and 4.

On that part of the axle e which intervenes between the spiral blades orthreads of the screwagreat number of holes are drilled into theinterior. (Shown at 12.) These holes extend entirely around the axle ata distance of a few inches apart, and are for the purpose of ad mittingjets of airin between the convolutions of the screw.

The action of the apparatus is as follows: The tank a is first filledwith water by the opening at, and steam is admitted to the pipe I),which consists of several lengths united by bends at each end, so as toform a continuous passage for the steam to rush through; or, instead ofthese pipes, fire may be applied to the under side of the tank a, theobject in either case being to heat the water, which forms a bath forthe sugar-pan, against the under side of which the water is in contact.Athermometer may be inserted in the opening or, for the purpose ofascertaining the temperature of the bath, which I prefer to use at 150Fahrenheit. The opening at is left open to the atmosphere, in order toprevent even with carelessness) the water from being raised above I forebeing allowed to crystallize, as already 212 Fahrenheit, andconsequently so as to prevent latent heat of steam from acting upon themetal against which the saccharine fluid is in contact; and although Ihave herein described water as being used as a heating medium, the heatmay be transmitted to the fluid in the pan by heated air, or by anyliquid or aeriform fluid whose temperature is below 212 Fahrenheit; orthe process of evaporation may be carried on by the application ofheated air to the fluid on the surfaces of the moving or revolvingapparatus without any application of heat to the bulk of fluid in thepan otherwise than what it may obtain from the revolving apparatus,which becomes heated by the air so brought in contact therewith.

I also use a blowing-fan or other convenient air-forcing apparatus,which I connect with a pipe. One end of this pipe is inserted into theopen end 6 of the hollow axis of the screw. The air so forced I preferto heat to about 150 Fahrenheit by the application of heat to the pipewhich conveys it to the evaporating apparatus, or by any convenient modeof heating air already known and practiced. The saccharine fluid is letinto the pan so as nearly to fill it. Rotary motion is then to becommunicated from any first mover to the axle c, which should revolve atthe rate of about eight or ten revolutions per minute. As the screwrevolves, it will take up upon its surface a thin coating of thesaccharine fluid, and as the heated air rushes out of the numerous holesin the hollow axle it will be brought in contact with the thin stratumoffluid thus presented to its action, the aqueous portions of the fluidwill be absorbed by the air and carried off in combination therewith,while the saccharine fluid on the screw, which has thereby become moredense, will again descend into and mix with the fluid, while freshportions are rising out of it, to be acted on in like manner. As thequantity of fluid in the pan diminishes by evaporation, fresh portionsshould be added until the requisite density is obtained.

To prevent the deposit of the'sugar, or the formation of a concrete masson the bottom of the pan, I cause the screw to'be fitted so as to comealmost in contact with the bottomof the pan,whereby the blades of thescrew will form a scraper and remove any such deposit or concrete matterto one end of the pan. This tendency to bring the charge to one end ofthe pan renders it necessary to leave room on both sides of the screw at0" and 0 for the fluid to return to the opposite end of the pan, andthus keep up a circulation of the fluid during the whole process. "Whenthe charge is sufiiciently concentrated, a sluice properly placed at oneend of the pan may be opened and the screw continued in motiomwhich willgreatly facilitate the discharge of the sirup from the pan, which canthen be refilled, and the process continued as before. After theconcentrated sirup leaves the pan, it should be heated bepracticed withsirups concentrated in the vacuum-pan. Although the apparatus hereinlast described may be used for effecting the final concentration of thecane-juice or other sac: charine fluids, I prefer to use it only for thepurpose of increasing the density of such fluids to 27 or 80 Baume, inwhich case the screw may be made to move an inch or two clear of thebottom of the pan, because no deposit of crystals will take place atthat density. The convolutions of the screw or the disks mayin that casebe made much closer together in consequence of the degree of fluiditypossessed by sirups of that density.

\Vhen two different pans are to be used, I prefer to construct the oneused for the final concentration of the sirup, as represented on Sheet Eof the drawings annexed,where Figure l is a crosssection of theinvention; Fig. 2, an end elevation of it; Fig. 3, a plan of it; Fig. i,a longitudinal section of it, and Fig. 5 a longitudinal elevation of it.Figs. 6 and 7 show a scraped used to cleanse the screws.

a is a tank or jacket, of cast-iron or other suitable material, in theupper part of which there are two large cylindrical hollows, a a,forming the sugar-pan, and which are of such a radius as to fit nearlyclose to the large screws b.

Between thelarge hollows a there is a smaller one, 0, which is for thepurpose of receiving the thick sirup,which is scraped off the spiralblade during the emptying of the pan. The axes b of the screws b arehollow, and perforated with numerous holes for the distribution of airbetween the blades of the screws. Each axis b is supported at oneendbybrass bearings in the plumber-box d, and the large open ends of theaxes bare each supported by three f riction-rollers, e, which work in acase,f,bolted to the end of the tank. The outer ends of the axes bllilNe spur-wheels gh keyed upon them.

On the end of the tank a, and midway between the two screws, there is aplumberblock, 1', which supports one end of the main driving-shaft j.This shaft has upon it a wheel, 75, that gears into both the wheels 9and it, so as to drive both the screws 12 in one direction. The screwsare made one right and the other left handed, so that each of them movethe sirup to opposite ends of the pan. At each end of the pan there is aspace of a few inches in width at (4*, which communicates with both ofthe screws, so that the sirup moved by one screw flows freely along thisspace and supplies the other screw, while the space at the opposite endin like manner allows the sirup propelled back again by the last-namedscrew to pass again into the first one, and thus a circulation of thefluid is obtained, which equalizes its temperature and density. hen theconcentration of the sirup is effected, the pan is to be emptied byreversing the motion of one of the screws, and thereby causing the sirupto be brought to that end of the pan where the sluice Z is provided fordrawing it off. To produce this change of motion there is a wheel, on,which moves freely on a fixed stud projecting from the end of the tanka, and is always in gear with the drivingwheel h of the screw. There isalso another wheel, a, which gears with the wheels g, 7;, and m. Thewheel a is supported on a fixed stud, which projects from the end of thetank a, and is made to slide backward or forward upon it. The wheel 7;is also arranged so as to slide endwise on its shaft, a forked lever, ifdesirable, being made to act on the wheels 75 and a, so as to slide themalong in opposite directions, in a manner well understood, so that whenthe wheel Z; is in gear with the wheels and h the wheel a will be out ofgear with the wheels is and g, and thus the screws will move both thesame way, as before described. By reversing the forked lever, the wheelIt will be thrown out of gear with the wheels 9 and 71/, while the wheela will be thrown in gear with the wheels g and m, and as the wheel a isof double the breadth of tooth to the others it will continue in gearwith the wheel 7t, and thus the wheels 7' and h, with their respectivescrews, will be carried round in opposite directions.

After the greater portion of the sirup has been run off by the sluice,it will be found that a considerable quantity of it is still leftadhering to the blades of the screws. In order to remove this portionalso, a scaper, formed as represented in Figs. 6 and 7 is placedbetweenthe convolutions of the screws 1) at that end farthest from thedischargingsluice. This scraper is shown by dotsin Fig. 1. Thesemi-fluid matter adhering to the screws will thus be.removed and bemade to flow into the gutter c, and from thence it will flow into thespace (0*, and escape by the sluice Z. As the screws revolve the scraperwill be carried along a distance equal to the breadth ofone convolutionevery time theyturn around, and thus the entire surface of both screwswill be cleansed by the action of one scraper.

The atmosphere of large towns (in which sugar-refineries are generallycarried on) has floating in it soot, 'dust, and other matters, which, ifblown with it on the wet surface of the screw, would render the sirupimpure and injure its color. I therefore force the air through silk,cotton, or woolen fabrics, and thus separate the solid matters from theair before allowing it to enter the screws. This filtration of the airmay be readily accomplished by causing the air from the blowingapparatus to enter at one side of a wind-chest, which has a centraldivision formed of some suitable textile fabric tightly stretched over aframe.

will collect and be carried off by a pipe proceeding from the oppositeside of the chest from that at which it entered, while the solid mattersfloating therein will be separated by the fabric, from the surface ofwhich they may be brushed from time to time.

Although the spiral blade or screw herein The air passing through thisfabric described affords great facility in discharging thecontents ofthe pan and in scraping the bottom of it, nevertheless plain circularplates or disks may be used instead, and as this difference will notaffect the general arrangements of the apparatus, I have shown only aport-ion of a hollow axle with plain disks. In Fig. 6, Sheet D, a is theaxle, o the disks, and w the holes through which heated air is forcedbetween the disks, to cause the evaporation of the fluid taken up upontheir surfaces; and although I prefer to force heated air from thecenter of such disks, it will nevertheless be ob vious that a similar,though less perfect, result may be obtained by forcing such heated airbetween disks mounted on a solid axis, as represented in I ig.,7, SheetD, where :0 represents the disks, 1 the solid axis, and z a pipe placedparallel thereto, and perforated on that side next to the disks, so thatheated air may be forced between and in contact with the wet surface ofthe revolving disks.

Although I have herein described the mode which I prefer of evaporatingsaccharine fluids by taking up thin films or coatings thereof uponrevolving surfaces, it will nevertheless be obvious that plates orsurfaces made to re ciprocate or otherwise move into and out of thefluid to be evaporated may also be made to take up the fluid upon themand expose it to the action of heated air, and may therefore be used asa means of carrying into effect this part of my invention; and, further,instead of using revolving or moving surfaces as a means of exposingthin films of saccharine fluid to the action of heated air, fixed platesor surfaces may be used in a vertical or inclined position without beingheated otherwise than by the heated air, which is forced between themfor the purpose of absorbing the aqueous portions of such fluids. Theseplates or surfaces may be placed in an upright tank or vessel open atthe top for the escape of the heated air and vapor, and connected atbottom with a pipe or trunk, through which heated air is forced by afaub] ower or other suitable means, and thus a strong current of heatedair will be made to sweep over the wet surfaces and produce a rapidevaporation.

The plates orsurfaces may be placed within a quarter or half an inch ofeach other, and the fluid allowed to flow onto the top end of them fromperforated pipes, in connection with a reservoir, which may be suppliedby a common lift-pump froma tank or vessel, into which the fluid fallsafter passing over the platesjand thus a repetition of the process maybe carried on until the fluid has arrived at the desired density.

I have not hereunto annexed any drawings of such apparatus because theform and arrangement thereof will be readily understood by any workman,and admits of great variation without affecting the principle on whichit depends.

It sometimes happens that, owing to eertain interruptions caused by thestate of the weather or by other circumstances, a portion of the crop ofcanes of an estate is in danger of being lost or spoiled unless they canbe used with great expedition, and whenever, from this or other causes,it is requisite to increase the evaporative power of the apparatusherein described, I either. increase the temperature of the air up to orabout 212 Fahrenheit, or I turn on steam from any suitable boiler intothe jacket or tank below the pan, the opening or openings on beingclosed for the purpose, and a pipe attached to the tank a in connectionwith a steam-boiler, to which mode of heating separately I make noclaim. I thus increase the rate of evaporation, considering itpreferable in such emergencies to produce an inferior sugar to allowingthe same to be entirely wasted from want of the means of suflicientlyrapid evaporation.

Having thus described the nature of my said invention and the manner ofconstructing the same, what I claim therein is as follows:

- ing the saccharine liquor, the apparatus for effecting its evaporationby means of hot air blown on thin or extended surfaces, and a screw orplates, as specified.

In testimony whereof I have hereto set my signature this 31st day ofDecember, A. D. 182.

IIENRY nEssEMER.

Vitnesses:

JosErH MAR UETTE, JOHN R. BARKER.

